It's over between us

However, the one-eyed man truly hadn't expected Ma Dong to actually enter a hidden base, and rush out on a bike...

There was no other way. If he had allowed Ma Dong to rush out into the wilderness, the one-eyed man and his subordinates would be utterly incapable of catching up to Ma Dong. They would have lost the chance to find out about the inventory of this secret base, and they wouldn't be able to know if there were other vehicles. Even if there were other vehicles for them to use, the sound from starting up those vehicles would immediately tip Ma DOng off to their presence. By then, would it still be possible for this "insane" fellow to allow himself to lead them to the remaining Assassin members? He might even deliberately lead them in the wrong direction.

Therefore, the one-eyed man had no choice but to personally take action to stop Ma Dong.